In the art of pumps such as stomach pumps and the like, it is well known to provide a manually operable pumping apparatus which includes a squeeze bulb having valve elements which operate under the impetus of fluid pressure within the pumping apparatus to provide for unidirectional flow within the pumping apparatus. For example, a stomach pump of the type characterized is known to have such a bulb and check valve elements at the inlet and outlet of the resilient bulb to provide for a positive flow pumping action as shown in U.S. Pat. No. 598,407. Other such pumps or syringe apparatus are disclosed by U.S. Pat. Nos. 386,603 and 179,950.
Also known is a pump apparatus for use as a pleuro-peritoneal shunt which includes a flexible pump chamber containing two miter valves therein, the pump chamber being disposed between two lengths of catheter. Such a shunt apparatus is offered by Denver Biomaterials Inc., for example.
One way flow check valves for use in medical and other apparatus for such purposes as stomach pumping, drainage of the chest, apparatus inflation, and a variety of other purposes are disclosed in U.S. Pat. Nos. 3,463,159, 15,192, 3,133,696, and 4,607,663. Still other syringe or air bulb structures are disclosed in U.S. Pat. Nos. 2,064,619 and 451,179.